Biology Unit 2.5 - Proteins-their functions and uses

Biology Unit 2.5 - Proteins-their functions and uses

1. Proteins

   • Protein molecules are made up of LONG CHAINS of AMINO ACIDS. These long chains are folded to produce a specific shape that enables other molecules to fit into the protein.
     • Proteins act as...
       • Hormones
       • Antibodies
       • Structural components of tissues such as muscles
       • Catalysts

2. Enzymes

   • The shape of an enzyme is vital for the enzyme's function
     • High temperatures can change the shape
   • Different enzymes work best at different pH values.
   • Some enzymes work outside the body cells
     • The digestive enzymes are produced by specialised cells in glands and in the lining of the gut.
       • The enzymes then pass out of the cells into the gut where they come into contact with food molecules
         • They catalyse the breakdown of large molecules into small molecules
   • Amylase is produced in the salivary glands, the pancreas and the small intestine
     • This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine
   • Protease enzymes are produced by the stomach, the pancreas and the small intestine.
     • These enzymes catalyse the breakdown of proteins into amino acids in the stomach and small intestine
   • Lipase enzymes are produced by the pancreas and small intestine.
     • These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine
   • The stomach produces hydrochloric acid. The enzymes in the stomach work most effectively in these acid conditions
   • The liver produces bile, which is stored in the gall bladder before being released into the small intestine.
     • Bile neutralises the acid that was added to food in the stomach
       • This provides alkaline conditions in which enzymes in the small intestine work most effectively
   • Some microorganisms produce enzymes that pass out of the cells. These enzymes have many uses in the home and in industry
     • At home...
       • Biological detergents may contain protein-digesting and fat-digesting enzymes (proteins and lipases)
       • Biological detergents are more effective at low temperatures than other types of detergents
     • In industry...
       • Proteases are used to 'pre-digest' the protein in some baby food
       • Carbohydrates are used to convert starch into sugar syrup
       • Isomerase is used to convert glucose syrup into fructose syrup, which is much sweeter and therefore can be used in smaller quantities in slimming foods
       • In industry, enzymes are used to bring about reactions at normal temperatures and pressures that would otherwise require expensive, energy-demanding equipment. However most enzymes are denatured at high temperatures and many are costly to produce